Valve, in particular for an internal combustion engine

ABSTRACT

A valve ( 1 ), in particular for a combustion engine, comprising:—a body ( 2 ) in which the following are provided: a housing ( 8 ) in which at least one bearing is arranged, and a conduit ( 3 ) designed to be traversed by a fluid, and—a shutter ( 5 ) mounted pivoting in the body ( 2 ) by a pin ( 7 ) received with radial clearance in the bearing, the shutter ( 5 ) pivoting between:—an open position, and—a closed position in which it comes into contact with the body ( 2 ) via a first contact area of the shutter located on a first side of the pin ( 7 ) and via a second contact area of the shutter located on a second side of the pin ( 7 ) opposite said first side, the switching of the shutter ( 5 ) from the open position to the closed position being accompanied by a radial movement of the pin ( 7 ) in the bearing.

The present invention concerns a valve, in particular for an internalcombustion engine.

The invention in particular applies when the internal combustion engineis used for the propulsion of a vehicle, for example a motor vehicle. Itmay be an engine the fuel of which is petrol or diesel. The valve may beintegrated into the air circuit of the internal combustion engine.

In the context of the invention, the “internal combustion engine aircircuit” means the circuit between the admission inlet and the exhaustoutlet of the internal combustion engine. The valve may be in theadmission circuit, the exhaust circuit, or a recirculation loop throughwhich exhaust gas recirculation (EGR) gases pass.

In the case of a valve including:

-   -   a body including a duct in which a fluid flows, and    -   a shutter mounted to be mobile in the body between an open        position and a closed position in which it has to block the        duct,        there are problems of the valve leaking when the shutter is in        the closed position. To solve these problems, it is known to use        a seal that is disposed between the body and the shutter when        the latter is in the closed position. However, a seal of this        kind is liable to expand because of the high temperatures that        can be reached in its environment.

Another solution to this problem linked to the use of a seal is to bringthe shutter directly into contact with the body when the shutter is inthe closed position. However, a dimensional constraint between theshutter and the part of the duct in which it moves must be complied withto prevent the shutter from being wedged against the wall of said partof the duct before reaching the closed position, as is describedhereinafter with references to FIGS. 24 and 25.

In those figures, the body 102 has a sealing plane P coming into contactwith a sealing plane P′ of the shutter 105 when the shutter is in theclosed position to block the duct 103 in the body 102. Because of therigid nature of the contacts between the shutter and the body, it isfound that the shutter 105 is prevented from being wedged against thewall of the body 102 if the distance Dv measured between the center ofthe pin 107 enabling the shutter 105 to pivot in the body 102 and thesealing plane P′ of the shutter 105 is less than or equal to thedistance Dc measured between the center of the housing 108 of the body102 in which the pin 107 is received and the sealing plane P of the body102.

This dimensional constraint must further be weighted to allow forinaccuracies in respect of the dimensions of the various components ofthe valve during manufacture thereof. Because of this weighting, theremay be relatively large empty sections between the body and the shutterwhen the shutter is in the closed position, these empty sections, alsoknown as “leakage sections”, potentially causing leaks greater than whatcan be tolerated when the valve is in the closed position.

There exists a requirement for a valve that is relatively simple tomanufacture and effectively overcomes the disadvantages referred toabove.

An object of the invention is to address this requirement and, in one ofits aspects, it does so by means of a valve, in particular for aninternal combustion engine, comprising:

-   -   a body including: a housing in which is disposed at least one        bearing and a duct adapted to have a fluid pass through it, and    -   a shutter mounted to pivot in the body by means of a pin        received with radial play in the bearing,        the shutter pivoting between:    -   an open position, and    -   a closed position in which it comes into contact with the body        in a first contact area of the shutter on a first side of the        pin and in a second contact area of the shutter on a second side        of the pin opposite said first side,        the passage of the shutter from the open position to the closed        position being accompanied by radial movement of the pin in the        bearing.

The above valve makes it possible to prevent the shutter from beingwedged against the wall of the duct when the shutter goes to the closedposition without it being necessary to comply with any excessivedimensional constraint between the shutter and the part of the duct inwhich it moves.

This dimensional constraint is reduced thanks to the use of the play ofthe bearing(s), which constitutes an adjustment variable with regard toinaccuracies in the dimensions of the various components of the valveduring manufacture thereof.

The shutter is preferably not directly in contact with the body when itis in the open position.

When it moves, the shutter may be in a single closed position, in whichit comes into contact with the body. The valve may be a valve in theadmission circuit of the internal combustion engine, in the exhaustcircuit of the internal combustion engine, or in an exhaust gasrecirculation loop enabling the latter gases to be re-injected into theadmission side of the internal combustion engine. This recirculationloop may be a “low-pressure” loop or a “high-pressure” loop.

The valve is in particular a so-called “two-port” valve.

Alternatively, the valve may be a so-called “three-port” valve. Thevalve may then be at the inlet of the recirculation loop, that is to sayat the place in the exhaust circuit at which the recirculation loopstarts. The so-called “three-port” valve may alternatively be at theoutlet of the recirculation loop, that is to say at the place in theadmission circuit where the exhaust gases are re-injected into theadmission side.

The valve may therefore be at most a three-port valve.

The closed position, in which the shutter blocks the duct, and the openposition may each be an extreme position for the pivoting of theshutter. In other words, the pivoting of the shutter between the openposition and the closed position defines the maximum amplitude of themovement in rotation of the shutter.

There is advantageously no flexible element of the valve between theshutter and the body when the shutter is in the closed position. Here“flexible” is used in contrast to “rigid”, the body and the shutter thenbeing rigid.

A flexible element of this kind is a seal, for example. The shutter andthe pin may be connected by a support extending along at least a portionof the pin. The pin and the shutter may be in different planes.

The valve therefore has a pin offset relative to the shutter, incontrast to valves in which the pin and the shutter are in the sameplane.

Alternatively, the pin and the shutter may be in the same plane.

The body may have a sealing plane of the body coming into contact withthe first and/or second contact area of the shutter when the shutter isin the closed position and the first and/or the second contact area ofthe shutter may be in a sealing plane of the shutter.

The first contact area of the shutter may be in a sealing plane of theshutter other than a plane intersecting the axis.

The second contact area of the shutter may be in another sealing planeof the shutter other than a plane intersecting the axis.

When the shutter is in the closed position, the sealing plane of thebody and the sealing plane of the shutter have at least one point ofcontact. The radial play of the bearing(s) may distance a portion of theshutter from the sealing plane of the body when the shutter goes to theclosed position.

The distance between the center of the housing and the sealing plane ofthe body may be greater than the distance between the center of the pinand the sealing plane of the shutter. This dimensional constraint, whichis generally imposed, makes it possible to prevent the shutter frombeing wedged against the wall of the duct when the shutter goes to theclosed position. If this constraint is complied with, no play in thebearing is necessary to prevent the shutter from being wedged againstthe wall of the duct. The second area of contact of the shutter againstthe body can make it possible to prevent excessive movement of the pinin the bearing and thus to prevent excessively large leakage sectionsexisting when the shutter is in the closed position. This thereforereduces the use of the radial play available in the bearing(s), giventhat the movement of the shutter because this play to prevent wedging isthen not necessary.

Alternatively, the distance between the center of the housing and thesealing plane of the body may be less than the distance between thecenter of the pin and the sealing plane of the shutter. This situationcan arise even though an attempt has been made to comply with the abovedimensional constraint, because of inaccuracies in the dimensions of thecomponents of the valve during manufacture thereof. If no play of thebearing(s) is used, this situation leads to wedging of the shutteragainst the wall of the duct when the shutter goes to the closedposition, which normally prevents the use of any such valve. Using theplay in the bearing(s) makes it possible to revert to the previoussituation in which there is no wedging.

Thus the invention can make it possible nevertheless to use valves inwhich, for reasons of inaccuracies in the dimensions of the componentsof the valve during manufacture thereof, the above dimensionalconstraint between the shutter and the wall of the body in which itmoves are not complied with.

The play in the bearing(s) may be sized to be greater than or equal to apredefined overall inaccuracy for the shutter and the part of the ductin which the shutter moves, this predefined overall inaccuracy resultingin particular from the linear combination of predefined individualinaccuracy for each side of the shutter and the part of the duct inwhich the shutter moves. Each predefined overall inaccuracy is forexample fixed as a function of feedback in respect of the technique usedto manufacture the corresponding component of the valve.

The predefined overall inaccuracy may be obtained by adding thepredefined individual inaccuracies for the following dimensions:

-   -   distance between the center of the housing and the sealing plane        of the body,    -   distance between the center of the pin and the sealing plane of        the shutter,    -   thickness of the shutter,    -   height of a groove in the duct, one part of the shutter in which        the second area of contact is situated in the closed position        moving in this groove when the shutter goes from the open        position to the closed position.

In accordance with a first embodiment of the invention, the first and/orsecond contact area of the shutter forms a line contact with the bodywhen the shutter is in the closed position.

Each contact area of the shutter may form a line contact with the bodywhen the shutter is in the closed position.

In accordance with this first embodiment of the invention, only thefirst contact area of the shutter can come into contact with the sealingplane of the body when the shutter is in the closed position. The secondcontact area of the shutter may be in another plane of the shutter andcome into contact with the body elsewhere than in the sealing plane ofthe body when the shutter is in the closed position. The sealing planeof the shutter and this other plane of the shutter may then be parts ofopposite faces of the shutter, the latter in particular taking the formof a plate.

The shutter may have a rectangular shape in section, the first contactarea and the second contact area being on opposite sides of the shutter.

Alternatively, the shutter may have a half-moon shape in section thediameter of which is extended by a rectangle and the first area ofcontact may be on the circle of the half-moon and the second contactarea carried by the side of the rectangle opposite the side of therectangle coinciding with the diameter of the half-moon.

When the part of the shutter carrying the second contact area in theclosed position moves in a groove in the body and forming part of theduct, the second contact area can then contact the bottom of the grooveformed by said other plane.

In accordance with a second embodiment of the invention, the firstand/or second contact area of the shutter may form a plane contact withthe sealing plane of the body when the shutter is in the closedposition.

For example, each contact area of the shutter forms a plane contact withthe sealing plane of the body when the shutter is in the closedposition.

The first and second contact areas of the shutter may be in the sealingplane of the shutter and each of said contact areas of the shutter thencontacts the sealing plane of the body when the shutter is in the closedposition. The shutter may then be a self-centering shutter, by virtue ofthe fact that the contacts between the shutter and the body occur in asingle plane when the shutter is in the closed position and radial playexists in the bearing(s). With such a valve, when the shutter is in theclosed position, the contacts between the shutter and the body canenable immobilization of the pin without the latter being in contactwith the bearing(s).

The sealing plane of the shutter may a plane other than a planeintersecting the pin.

In accordance with this second embodiment of the invention, the firstcontact area of the shutter may be carried by a first part of theshutter and be part of the upper face of said first part and the secondcontact area of the shutter may be carried by a second part of theshutter and be part of the lower face of said second part. In otherwords, in accordance with this second embodiment of the invention, thefirst and second contact areas may be parts of opposite faces of theshutter whilst being in the same plane.

Each of the first and second parts may be a separate part, said partsbeing rigidly coupled to each other to form the shutter. Each of theseparts is a plate, for example. Said parts are in particular rigidlycoupled to each other at the level of the sealing plane of the shutter.

In accordance with this second embodiment of the invention, the part ofthe duct in which the shutter moves may be formed in two parts of thebody rigidly coupled to each other at the level of the sealing plane ofthe body. Part of the sealing plane of the body may be defined by theupper face of one of these parts of the body, which then comes intocontact with the part of the lower face of the second part of theshutter forming the second contact area when the shutter is in theclosed position whereas another part of the sealing plane of the bodymay be defined by the lower face of another part of the body which thencomes into contact with the part of the upper face of the first part ofthe shutter forming the first contact area when the shutter is in theclosed position.

In accordance with the second embodiment of the invention, the length ofthe second part of the shutter measured along the pin may be less thanthe length of the first part of the shutter measured along the pin. Theshutter is then formed by two parts of different length and the lengthof the first part can be such that in the closed position no leakageoccurs at the level of this first part and only the second part causesleaks.

The invention may be better understood by reading the followingdescription of nonlimiting embodiments thereof and examining theappended drawings, in which:

FIGS. 1 to 11 relate to a valve in accordance with a first embodiment ofthe invention, FIGS. 1 and 2 representing the valve in elevation, FIG. 3representing the shutter and the pin separately, FIG. 4 being a planview of the valve from FIG. 1, FIGS. 5 to 7 representing in sectiontaken along the line A-A a first valve similar to that from FIG. 4,FIGS. 8 to 10 representing in section taken along the line A-A a secondvalve similar to that from FIG. 4, and FIG. 11 diagrammaticallyrepresenting a valve in accordance with the first embodiment of theinvention when it is of the “three-port” type,

FIGS. 12 to 23 relate to a valve in accordance with a second embodimentof the invention, FIGS. 12 and 13 representing the valve in elevation,FIG. 14 representing the shutter and the pin separately, FIG. 15 being aplan view of the valve from FIG. 12, FIGS. 16 to 18 representing insection taken along the lines A-A, B-B and C-C a first valve similar tothat from FIG. 15, FIGS. 19 to 21 representing in section taken alongthe lines A-A, B-B and C-C a second valve similar to that from FIG. 15,FIG. 22 representing the valve from FIG. 15 in an exaggerated manner,

FIG. 23 diagrammatically representing a valve in accordance with thesecond embodiment of the invention when it is of the “three-port” type,and

FIGS. 24 and 25 have already been described.

There has been represented in FIG. 1 a valve 1 covered by the invention.In this figure the valve 1 is a so-called “two-port” valve but theinvention is not limited thereto, as emerges hereinafter.

The valve 1 that is to be described is a valve used in an air circuit ofan internal combustion engine, used for example to propel a motorvehicle.

The valve 1 includes a body 2, for example made from aluminum, steel,plastic or stainless steel, in which is formed a duct 3. This is forexample an admission duct, an exhaust duct or a duct forming an exhaustgas recirculation (EGR) loop, which can be a high-pressure loop or alow-pressure loop. The body 2 of the valve may be made by assembling twoparts 2 a and 2 b, these two parts being in contact on a plane P ofwhich one wall defines a part of the duct 3, as emerges hereinafter. Theplane P is referred to as the “sealing plane” of the body 2 hereinafter.The part 2 b has not represented in FIG. 2.

In the example considered gases that can reach a high temperature, forexample up to 700° C., pass through the duct 3.

As represented in FIGS. 1 and 2, the valve 1 includes a shutter 5disposed in the body and mounted to pivot thanks to a pin 7 received ina housing 8 of the body 2 by means of one or more bearings that are notrepresented. The pin 7 extends in a direction X and the bearing(s) haveradial play in the direction X allowing the pin 7 to move in the bearingand in the housing 8 perpendicularly to the direction X. FIG. 3represents the shutter 5 and the pin 7 separately. As can be seen inFIG. 3, the shutter can take the form of a cylinder of circular crosssection. In the example described a support 9 extending radiallyrelative to the pin 7 connects the pin 7 and the shutter 5.

In the FIG. 3 example, the shutter 5 is globally plane and perpendicularto the direction of the support 9.

As emerges hereinafter, the shutter 5 has two areas 11 and 12 of contactwith the body 2 when it is the closed position. The first contact area11 is on a first side of the pin 7, that is to say a first side of thesupport 9 here and the second contact area 12 is on a second side of thepin 7, that is to say a second side of the support 9 here. The secondcontact area 12 is carried by a portion of the shutter moving in agroove 13 formed in the duct 3. Here the second contact area 12 comesinto contact with the bottom of the groove 13.

The distance between the center of the housing 8 and the sealing plane Pof the body 2 is designated “Dc”. In the example shown in FIGS. 1 to 11,the upper face of the shutter 5 defines a joint plane P′ of the shutter5, as explained hereinafter, and the distance between the center of thepin 7 and this plane P is designated “Dv”.

In the example shown in FIGS. 5 to 7, the distance Dc is less than Dv,that is to say the sealing plane P′ of the shutter is farther from thesealing plane P of the body from the pin 7. In the prior art, such aconfiguration, which can be explained by the margins of error in respectof the dimensions of the various components of the valve 1 duringmanufacture thereof, prevents the shutter 5 from reaching its closedposition, the shutter being wedged against the wall of the duct 3 beforeit can reach the closed position.

In FIG. 5, the shutter 5 is still in the open position and gases cancirculate in the duct 3 and through the valve 1. Here the shutter 5 isnot in contact with the body 2, neither the first contact area 11 northe second contact area 12 coming into contact with the body 2.

In FIG. 6, the shutter 5 is moving toward the closed position bypivoting of the pin 7 in the housing 8. Contact is then establishedbetween the shutter 5 and the body 2 of the valve 1.

As can be seen in FIG. 7, in contrast to the prior art valves, the factthat the sealing plane P′ of the shutter 5 is farther than the sealingplane P of the body 2 from the pin 7 does not prevent the shutter 5 fromreaching a closed position in which it comes into contact with the body2 in two separate areas 11 and 12. In fact, as represented in FIG. 7,because of the closing torque applied to the shutter by an actuator thatis not represented, the pin 7 moves radially relative to the direction Xin the housing 8, with the result that the positions relative to the pin7 of the sealing plane P′ of the shutter 5 and the sealing plane P ofthe body 2 are modified and the contact that can be seen in FIG. 6between the shutter 5 and the body does not prevent the shutter 5 fromcontinuing to move toward the closed position.

In this example the shutter comes into contact with two separate wallsof the duct 3. In this first embodiment of the invention only the firstcontact area 11 is in the sealing plane P′ of the shutter 5 and in thisembodiment only this first contact area 11 comes into contact with thesealing plane P of the body 2.

In this embodiment there is therefore only one area of contact betweenthe sealing plane P of the body 2 and the sealing plane P′ of theshutter 5.

Here the second contact area 12 is in a plane parallel to the sealingplane P′ of the shutter 5 and defining the face of the shutter 5opposite that formed by the sealing plane P′.

The play in the bearing(s) making it possible to prevent the shutter 5from being wedged against the wall of the body 2 when the shutter 5 goesto the closed position is determined taking into account theinaccuracies in respect of the following dimensions, for example:

-   -   distance Dv,    -   distance Dc,    -   thickness e of the shutter 5 in the second contact area 12,    -   height h of the groove 13.

In this example the play in the bearings is chosen to prevent wedging ofthe shutter 5 in the following extreme cases because of the dimensionalinaccuracies:

-   -   (i) maximum Dc, minimum Dv, maximum h and minimum e,        corresponding to potential interference at the top of the        bearings,    -   (ii) minimum Dc, maximum Dv, minimum h and maximum e,        corresponding to potential interference at the bottom of the        bearings.

Four dimensions may be taken into account for the distance Dv, i.e. fourindividual levels of inaccuracy to be defined:

-   -   the straightness of the pin 7, for which an individual level of        inaccuracy of 0.02 mm in respect of the diameter of the pin 7 is        set, for example,    -   the position of the driving flats on the pin 7, for which an        individual level of inaccuracy of 0.1 mm is set, for example,    -   the position of the driving flats on the pin 5, for which an        individual level of inaccuracy of 0.04 mm is set, for example,        and    -   the position of the sealing plane P′ of the shutter 5, for which        an individual level of inaccuracy of 0.04 mm is set, for        example.

Two dimensions are to be taken into account for the distance Dc, i.e.two individual levels of inaccuracy to be defined:

-   -   the position of the sealing plane P of the body 2, for which an        individual level of inaccuracy of 0.1 mm is set, for example,        and    -   the coaxial relationship of the bearings, for which a level of        inaccuracy of 0.04 mm in respect of the diameter of the bearings        is set, for example.

There is therefore a variation of ±0.10 mm in Dv and ±0.07 mm in Dc.

In the extreme case (i), the compensation of play available in theupward direction must be at least (+0.07)−(−0.1)=0.17 mm in the exampleconsidered.

In the extreme case (ii), the compensation of play available in thedownward direction must be at least (−0.07)−(+0.1)=−0.17 mm.

A predefined overall error margin of 0.34 mm is therefore obtained, as aresult of which the bearings are sized so that each of them offers atleast 0.34/2 mm, i.e. 0.17 mm, of radial play in this example.

FIGS. 8 to 10 also represent the valve 1 when the shutter 5 goes fromthe open position to the closed position. In contrast to the examplethat has just been described, the distance Dc is greater than thedistance Dv, that is to say the sealing plane P′ of the shutter isnearer the pin 7 than the sealing plane P of the body. In this case, incontrast to the previous case, it is not necessary to modify therelative positions of the sealing plane P′ of the shutter 5 and thesealing plane P of the body 2 relative to the pin 7 to enable theshutter 5 to reach the closed position.

The second contact area 12, on the side of the pin 7 opposite the sidebearing the first contact area 11, makes it possible to preventexcessive radial movement of the pin 7 in the housing 8. The secondcontact area in fact comes to bear against the bottom of the groove 13,preventing further movement of the pin 7 in the bearing because of theclosing torque applied by the valve actuator. This therefore preventsserious leaks when the shutter 5 is in the closed position because ofthis movement linked to the existence of the radial play in thebearings.

In accordance with this first embodiment of the invention, when theshutter is in the closed position the shutter 5 forms a line contactwith the body 2 in the first contact area 11 and in the second contactarea 12.

The embodiments shown FIGS. 1 to 10 relate to a so-called “two-port”valve. However, the first embodiment of the invention also coversso-called “three-port” valves, as FIG. 11 shows. In this figure, theduct 3 comprises an inlet 20, a first outlet 21 and a second outlet 22.For example, the first outlet 21 allows the gases circulating in theexhaust circuit to continue their path in the latter and the secondoutlet 22 opens into a recirculation loop to the admission side of theengine. In this example, the shutter 5 of the valve 1 from FIGS. 1 to 10has an extension 24 extending beyond the part of the shutter 5 includingthe second area 12, so that the latter is disposed between saidextension 24 and the part of the shutter including the first area 11.

In FIG. 11, the shutter 5 is in a position in which the exhaust gasesrecirculate in the EGR loop. The extension 24 partially blocks thepassage toward the first outlet 21, in order to create a back-pressurefor maintaining sufficient pressure on the upstream side of the valve 5to enable a high flow rate toward the second outlet 22.

A valve 1 in accordance with a second embodiment of the invention isdescribed next with reference to FIGS. 12 to 22.

FIGS. 12 to 15 are similar to FIGS. 1 to 4. In accordance with thissecond embodiment, the shutter 5 comprises two portions 30 and 31 formedby separate parts fastened together. Each of these parts is in the formof a plate and the upper face 32 of the plate 30 lies against the lowerface 33 of the plate 31 without these plates 30 and 31 being exactlysuperposed. In this example, the upper face 32 of the plate 30 and thelower face 33 of the plate 31 are coplanar and be in the sealing planeP′ of the shutter 5. The sealing plane P of the body 2 is similar tothat described with reference to the first embodiment of the invention.Screws 35 are used to fix the plate 31 to the plate 30, for example.

In the embodiment represented the plate 30 is nearer the pin 7 than theplate 31 and here the plate 30 is connected to the support 9.

Here the upper face of the shutter 5 is defined by the portion of theupper face 32 of the plate 30 not facing the plate 31 and by the upperface of the plate 31 and the lower face of the shutter 5 is defined bythe lower face of the plate 30 and by the portion of the lower face 33of the plate 31 not facing the plate 30.

Still in this embodiment, and as can be seen in FIG. 14, the length l1of the plate 30 as measured in the direction X is greater than thelength l2 of the plate 31.

In accordance with this second embodiment of the invention, the twoparts 2 a and 2 b of the body are rigidly coupled to each other at thelevel of the sealing plane P of the body 2.

FIGS. 16 through 18 each represent three views in section of a positionof the shutter 5 when Dv is greater than Dc.

In FIG. 16, the shutter 5 is in the open position and is not in contactwith the body 2. In FIG. 17, the shutter 5 is going from the openposition toward the closed position and the upper face 32 of the plate31 is on the point of coming into contact with the sealing plane P ofthe body 2, this contact causing wedging of the shutter 5 in the duct 3in the prior art.

As can be seen in FIG. 17, thanks to the radial play in the bearing(s),the pin 7 is able to move radially, allowing the plate 30 to move awayfrom the sealing plane P of the body 2. The shutter 5 can continue itsmovement until it reaches the closed position in which it comes intocontact with the sealing plane P of the body 2 via the first area 11 andthe second area 12. Here the first area 11 is on the upper face 32 ofthe plate 30 and the second area 12 is on the lower face 33 of the plate31. The first area 11 and the second area 12 are therefore in the sameplane, namely the sealing plane P′ of the shutter 5. Here the contactbetween the shutter 5 and the body 2 via the first and second areas 11and 12 is plane, occurring exclusively between the respective sealingplanes P and P′.

For example, the play in the bearing(s) for preventing the shutter 5from being wedged against the wall of the body 2 when the shutter 5 goesto the closed position is determined in accordance with this secondembodiment of the invention by taking into account the inaccuracies inrespect of the following dimensions:

-   -   distance Dv, and    -   distance Dc.

In this embodiment the play in the bearings is chosen so that itprevents wedging of the shutter 5 in the following extreme casesresulting from dimensional inaccuracies:

-   -   (i) maximum Dc, minimum Dv, corresponding to potential        interference at the top of the bearings,    -   (ii) minimum Dc, maximum Dv, corresponding to potential        interference at the bottom of the bearings.

Four dimensions are to be taken into account for the distance Dv, i.e.four individual levels of inaccuracy to be defined:

-   -   the straightness of the axis 7, for which an individual level of        inaccuracy of 0.02 mm in respect of the diameter of the pin 7 is        set, for example,    -   the position of the driving flats on the pin 7, for which an        individual level of inaccuracy of 0.1 mm is set, for example,    -   the position of the driving flats on the shutter 5, for which an        individual level of inaccuracy of 0.04 mm is set, for example,        and    -   the position of the sealing plane P′ of the shutter 5, for which        an individual level of inaccuracy of 0.04 mm is set, for        example.

Two dimensions are to be taken into account for the distance Dc, i.e.two individual levels of inaccuracy to be defined:

-   -   the position of the sealing plane P of the body 2, for which an        individual level of inaccuracy of 0.1 mm is set, for example,        and    -   the coaxial relationship of the bearings, for which a level of        inaccuracy of 0.04 mm in respect of the diameter of the bearings        is set, for example.

There is therefore a variation of ±0.1 mm in Dv and ±0.07 mm in Dc.

In the extreme case (i), the compensation of play available in theupward direction must be at least (+0.07)−(−0.1)=0.17 mm in the exampleconsidered.

In the extreme case (ii), the compensation of play available in thedownward direction must be at least (−0.07)−(+0.1)=−0.17 mm.

There is therefore obtained a predefined overall error margin of 0.34mm, which means that the bearings are sized so that each of them offersat least 0.34/2 mm, i.e. 0.17 mm, of radial play in this example.

FIGS. 19 to 21 are similar to FIGS. 16 to 18 but correspond to a valve 1in which Dv<Dc, i.e. the sealing plane P′ of the shutter 5 is nearer thepin 7 than the sealing plane P of the body 2. As represented in FIG. 22,which represents the valve 1 in accordance with the second embodiment ofthe invention in plan view with the difference between the length l1 ofthe plate 30 and the length l2 of the plate 31 exaggerated; by virtue ofthe different lengths l1 and l2, in the closed position there are twoleakage sections S on respective opposite sides of the plate 31.

Although the second embodiment of the invention described withreferences to FIGS. 12 to 21 relates to so-called “two-port” valves, thesecond embodiment of the invention also covers so-called “three-port”valves, as can be seen in FIG. 22.

The invention is not limited to the embodiments that have just beendescribed.

Unless otherwise specified, the expression “including a” must beunderstood as synonymous with the expression “including at least one”.

1. A valve for an internal combustion engine, comprising: a bodyincluding: a housing in which is disposed at least one bearing and aduct adapted to have a fluid pass through it, and a shutter mounted topivot in the body by means of a pin received with radial play in thebearing, the shutter (5) pivoting between: an open position, and aclosed position in which the shutter comes into contact with the body ina first contact area of the shutter on a first side of the pin and in asecond contact area of the shutter on a second side of the pin oppositesaid first side, the passage of the shutter from the open position tothe closed position being accompanied by radial movement of the pin inthe bearing.
 2. The valve as claimed in claim 1, wherein the valve lacksany flexible element disposed between the shutter and the body when theshutter is in the closed position.
 3. The valve as claimed in claim 1,wherein the shutter and the pin are connected by a support extendingalong at least a portion of the pin.
 4. The valve as claimed in claim 1,the body having a sealing plane of the body coming into contact with thefirst contact area and/or the second contact area of the shutter whenthe shutter in the closed position and the first contact area and/or thesecond contact area of the shutter being in a sealing plane of theshutter.
 5. The valve as claimed in claim 4, wherein the distancebetween the center of the housing and the sealing plane of the body isgreater than the distance between the center of the pin and the sealingplane of the shutter.
 6. The valve as claimed in claim 4, wherein thedistance between the center of the housing and the sealing plane of thebody is less than the distance between the center of the pin and sealingplane of the shutter.
 7. The valve as claimed in claim 1, wherein thefirst contact area and/or the second contact area of the shutter form aline contact with the body when the shutter is in the closed position.8. The valve as claimed in claim 7, wherein the shutter has arectangular shape and the first contact area and the second contact areabeing on opposite sides of the shutter.
 9. The valve as claimed in claim7, wherein only the first contact area of the shutter is in the sealingplane of the shutter, the second contact area of the shutter being inanother plane of the shutter.
 10. The valve as claimed in claim 9, thesealing plane of the shutter and said other plane of the shutter beingon opposite faces of the shutter.
 11. The valve as claimed in claim 1,wherein the first contact area and/or the second contact area of theshutter form a plane contact with the sealing plane of the body when theshutter is in the closed position.
 12. The valve according to claim 11,wherein the first contact area and the second contact area of theshutter are in the sealing plane of the shutter and each of said contactareas of the shutter contacts the sealing plane of the body when theshutter is in the closed position.
 13. The valve as claimed in claim 11,the first contact area of the shutter being on a first part of theshutter and on the upper face of said first part, the second contactarea of the shutter being on a second part of the shutter and on thelower face of said second part.
 14. The valve as claimed in claim 13,wherein the first part and the second part are rigidly coupled to eachother to form the shutter in the sealing plane of the shutter.
 15. Thevalve as claimed in claim 13, wherein the length of the second part ofthe shutter measured along the pin is less than the length of the firstpart of the shutter measured along the pin.
 16. The valve as claimed inclaim 4, the sealing plane of the shutter being a plane other than aplane intersecting the pin.
 17. The valve as claimed in claim 1, whereinthe valve is a three-port valve, and each of the open and closedpositions comprise an extreme position for the pivoting of the shutter.